Currently, various kinds of liquid thermosetting resins are used as an adhesive material for forming an adhesive layer. Forming a uniform adhesive layer on the surface of a workpiece requires a resin having a high degree of fluidity. Therefore, the resin used for this purpose is usually dissolved into, diluted with or dispersed in an organic solvent, water or other solvent. Using the liquid resin prepared by diluting a resin with an organic solvent or a similar solvent as described above, an adhesive layer is formed on the surface of the workpiece by dipping the workpiece in a reservoir containing the resin, or by spraying the resin onto the workpiece. An example of the liquid resins currently used is a thermosetting epoxy resin, containing 97% resin and 3% curing agent, diluted with methyl ketone.